mailbox: zynqmp: ipi mailbox driver

ZynqMP mailbox driver implementing IPI communication with PMU. This would
allow U-Boot SPL to communicate with PMUFW to request privileged
operations.

Signed-off-by: Ibai Erkiaga <ibai.erkiaga-elorza@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/mach-zynqmp/include/mach/sys_proto.h b/arch/arm/mach-zynqmp/include/mach/sys_proto.h
index 915badc..f25d414 100644
--- a/arch/arm/mach-zynqmp/include/mach/sys_proto.h
+++ b/arch/arm/mach-zynqmp/include/mach/sys_proto.h
@@ -54,6 +54,11 @@
 	TCM_SPLIT,
 };
 
+struct zynqmp_ipi_msg {
+	size_t len;
+	u32 *buf;
+};
+
 int zynq_board_read_rom_ethaddr(unsigned char *ethaddr);
 unsigned int zynqmp_get_silicon_version(void);